1. Field of the Invention
This invention relates to a flat shield harness having a function of shielding noise.
2. Description of the Related Art
A motor car that is a moving body includes a wire harness arranged to supply power from a power source such as a battery to electronic appliances such as various lamps and various motors mounted in the motor car, and feed a control signal to these appliances from a control device. The wire harness is composed of a plurality of electric wires. For example, a flat harness as shown in FIGS. 19 and 20 has been used as the wire harness.
As seen from FIGS. 19 and 20, a flat harness 101 is composed of a plurality of electric wires 102 in parallel to one another, a single drain wire 103, a metallic film 104 and a sheath 105. The electric wires 102 each consists of a conductive core 110 and a cladding 111 that clads the core 110. The core 110 is formed in a round shape in section, and made of copper or copper alloy. The cladding 111 is made of insulating synthetic resin. The plurality of electric wires 102 are arranged in parallel. Therefore, the cores 110 are also arranged in parallel.
The drain wire 103 is arranged in parallel to the plurality of electric wires. The drain wire 103 is formed in a round shape in section and made of conductive metal such as copper or copper alloy. The metallic film 104 is made of conductive metal such as copper or copper alloy, and formed as a thin film. The metallic film 104 covers the claddings 111 of all the electric wires 102 and is kept in contact with the drain wire 103.
The sheath 105 is made of insulting synthetic resin and sheathes the electric wires 102, drain wire 103 and metallic film 104. The flat harness 101 is formed in a belt in a state where the electric wires 102 and drain wire 103 are sheathed by the sheath 105.
In the flat harness 101, when external noise is about to invade the core 110 of each electric wire 102, it conducts to metallic film 104. The noise is dissipated outside the flat harness 101 through the drain wire 103. Thus, the metallic film 104 of the flat harness 101 can prevent the external noise from invading the core 110 of each electric wire 102.
Where the wire harness is assembled using the flat harness 101 as described above, each electric wire 102 is a xe2x80x9ccladded electric wirexe2x80x9d in which the electric wire is composed of the core 110 and the cladding 111, and the drain wire 103 is a xe2x80x9cbare electric wirexe2x80x9d which consists of only the core. Therefore, when the cladding 111 of the electric wire 102 is removed after the sheath 105 has been removed, the processing for the drain wire 103 is not required. Thus, when the cladding 111 of each electric wire 102 is removed, the drain wire 103 may be curved so that it does not become parallel to the core 110 of each electric wire 102 as seen from FIG. 19.
The cores 110 of the electric wires 102, which are parallel to each other, can be subjected to the processing in which they are equipped with a terminal metallic fitting as a single unit using a known crimping, caulking or inserting device and inserted into a connector housing. However, where the drain wire 103 is not parallel to the core 110 of each electric wire 102, it is difficult to connect the drain wire 103 to the terminal metal fitting using the above device.
Therefore, traditionally, the drain wire 103 was manually connected to the metal fitting by an operator, and each metal fitting was inserted individually into a connector housing. In this way, the conventional flat harness 101 increases a required number of man-hours in assembling the wire harness, which results in an increase in the production cost.
Further, in the above conventional technique, in order to dissipate the noise being about to invade the cores 110 of the electric wires, the drain wire 103 is connected to the thin metallic film 104 so that the contact therebetween becomes unstable in most cases. This makes it difficult to dissipate the noise trying to invade the core 110 of each electric wire 102 outside the flat harness 100.
A first object of this invention is to provide a flat shield harness which can surely dissipate externally the noise which is about to invade the core of an electric wire and suppress an increase in the cost in the wire harness to be assembled.
A second object of this invention is to provide a method for manufacturing such a flat shield harness.
In order to attain the first object, in accordance with the first aspect of this invention, there is provided a flat shield harness comprising:
a flat harness including a plurality of first conductive cores arranged in parallel and an insulating cladding which clads the first conductive cores;
a thin film sheet having a thin film conductive layer; and
an electric wire including a second conductive core and a second cladding which clads the second core,
wherein the thin film sheet is wound around the outer periphery of the flat harness with its ends superposed in a width direction of the flat harness, the electric wire is superposed on the ends, and the conductive layer at the ends of the thin film sheet at the ends is bonded to the second core.
In the above configuration, the thin film sheet is wound around the outer periphery of the flat harness with its ends superposed in a width direction of the flat harness, the electric wire is superposed on the ends, and the conductive layer at the ends of the thin film sheet at the ends is bonded to the second core. Therefore, the electric wire can be used as a drain wire.
Since the second core is bonded to the conductive layer of the thin film sheet, an electric connection can be made surely therebetween. Further, since the electric wire is superposed on the ends superposed on each other, the position where the ends are to be formed can be optionally selected.
In the above configuration, preferably, the thin film sheet has a thin insulating layer laminated to the thin conductive layer, and the insulating layer of the thin film sheet at the ends and the second cladding of the electric wire are welded to each other. This improves the mechanical strength of the bonding portion between the conductive layer and the second core.
In the configuration, the flat shield harness, further comprises a metallic plate interposed between and fixed to the ends of the thin film sheet, and the second core is bonded to the conductive layer and the metallic plate. This improves the mechanical strength of the bonding portion between the conductive layer and the second core.
In accordance with the second aspect of this invention, preferably, the thin film sheet is divided into a plurality of sub-sheets, ends of the sub-sheets are superposed on each other in a width direction of the flat harness, and the electric wire is superposed on one of the ends of the sub-sheets. In this configuration also, since the second core is bonded to the conductive layer of the sub-sheet, an electric connection can be made surely therebetween. Further, since the electric wire is superposed on the ends superposed on each other, the position where the ends are to be formed can be optionally selected.
In accordance with the first aspect to attain the second object, there is provided a method for manufacturing a flat shield harness comprising the steps of:
winding the thin film sheet around the outer periphery of the flat harness so that the conductive layer is located inside and the insulating layer is located outside and ends of the thin film sheet are superposed on each other;
superposing the electric wire on the ends of the conductor thin film; and
bonding the second core of the electric wire to the conductive layer of the thin film sheet by ultrasonic welding.
In this method, because the ultrasonic welding is performed, it is not necessary to remove a part of the second core of the electric core when the electric wire is attached to the thin film sheet.
Further, since the conductive layer and second core are bonded to each other by the ultrasonic welding, it is not necessary to use any other component which is separate from the thin film sheet and the flat harness. This suppresses an increase of the number of components constituting the flat shield harness. Further, during the ultrasonic welding, the insulating layer and the second cladding are molten so that they can be welded to each other.
In accordance with the first aspect to attain the second object, there is provided a method for manufacturing a flat harness comprising the steps of:
winding the thin film sheet around the outer periphery of the flat harness so that the conductive layer is located inside and the insulating layer is located outside and ends of the thin film sheet are superposed on each other;
superposing the electric wire on the ends of the conductor thin film with a metallic plate being interposed between the ends; and
bonding the second core of the electric wire to the conductive layer of the thin film sheet and the metallic plate by ultrasonic welding.
In this method, because the ultrasonic welding is performed, it is not necessary to remove a part of the second core of the electric core when the electric wire is attached to the thin film sheet.
Further, during the ultrasonic welding, the insulating layer and the second cladding are molten so that they can be welded to each other. Additionally, since the metallic plate is bonded to the second core and the conductive layer, the mechanical strength of the bonding portion between the second core and the conductive layer can be improved.
In accordance with the third aspect to attain the first object of this invention, there is provided a flat shield harness comprising:
a flat harness including a plurality of conductive cores arranged in parallel and an insulating cladding which clads the conductive cores;
a thin film sheet having a thin film conductive layer; and
wherein the thin film sheet is wound around the outer periphery of the flat harness, and the thin conductive layer of the thin film sheet is bonded to a selected core of the cores of the flat harness.
In accordance with this configuration, the single core can be used as a drain wire. Since the single core is bonded to the conductive layer of the thin film sheet, an electric connection can be made surely therebetween.
In the above configuration, preferably, the thin film sheet has an insulating layer laminated on the conductive layer, and with the conductive layer located inside and the insulating layer located outside, the thin film sheet is wound around the outer periphery of the flat harness. Because of such a structure, it is possible to prevent the thin film sheet and hence the single core serving as a drain wire from being short-circuited to the other electric wire and an electronic appliance outside the flat shield harness.
In accordance with the second aspect to attain the second object, there is provided a method for manufacturing a flat shield harness comprising the steps of:
winding the thin film sheet around the outer periphery of the flat harness so that the conductive layer is located inside and the insulating layer is located outside; and
bonding the conductive layer to the selected core by ultrasonic welding.
In this method, because the ultrasonic welding is performed, it is not necessary to remove a part of the second core of the electric core when the electric wire is attached to the thin film sheet.
Further, since the conductive layer and second core are bonded to each other by the ultrasonic welding, it is not necessary to use any other component which is separate from the thin film sheet and the flat harness. This suppresses an increase of the number of components constituting the flat shield harness. Further, during the ultrasonic welding, the conductive layer and the single core are bonded to each other, they can be surely metallic-bonded, thereby assuring the electric connection therebetween.
In accordance with the fourth aspect to attain the first object, there is provided a flat shield harness comprising:
a flat harness including a plurality of conductive cores arranged in parallel and an insulating cladding which clads the conductive cores;
a thin film sheet having a thin film conductive layer; and
a conductive metallic piece,
wherein the thin film sheet is wound around the outer periphery of the flat harness, the metallic piece is superposed on the outside of the conductive thin film sheet, and the metallic piece is bonded to the thin conductive layer of the thin film sheet and a selected core of the cores of the flat harness.
In accordance with this configuration, the single core can be used as a drain wire. Since the single core is bonded to the conductive layer of the thin film sheet, an electric connection can be made surely therebetween.
Additionally, since the metallic piece superposed on the outside of the conductive thin film sheet is bonded to the thin conductive layer of the thin film sheet and a selected core of the cores, the mechanical strength of the bonding portion between the conductive layer and the single core can be improved.
In the above configuration, preferably, the thin film sheet has an insulating layer laminated on the conductive layer, and with the conductive layer located inside and the insulating layer located outside, the thin film sheet is would around the outer periphery of the flat harness.
Because of such a structure, it is possible to prevent the thin film sheet and hence the single core serving as a drain wire from being short-circuited to the other electric wire and an electronic appliance outside the flat shield harness.
In accordance with the third aspect to attain the second object, there is provided a method for manufacturing a flat shield harness, comprising the steps of:
winding the thin film sheet around the outer periphery of the flat harness so that the conductive layer is located inside and the insulating layer is located outside;
superposing the insulating layer of the thin film sheet on the metallic piece so that the selected core of the flat harness is located on the conductive layer of the thin film sheet; and
bonding the conductive layer to the metallic piece and the selected core by ultrasonic welding.
In this method, because the ultrasonic welding is performed, it is not necessary to remove a part of the second core of the electric core when the electric wire is attached to the thin film sheet.
Further, since the conductive layer and second core are bonded to each other by the ultrasonic welding, it is not necessary to use any other component which is separate from the thin film sheet and the flat harness. This suppresses an increase of the number of components constituting the flat shield harness.
Further, during the ultrasonic welding, the conductive layer and the single core are bonded to each other, they can be surely metallic-bonded. Further, since the single core is bonded to both the conductive layer and the metallic piece, the mechanical strength of the bonding portion between the conductive layer and the single core can be improved, thereby assuring the electric connection therebetween.
In the above method, preferably, the ultrasonic welding is performed using a chip in a shape of a band-plate and an anvil having a flat plane, and with the metallic piece superposed on the flat plane and flat harness in contact with the chip, the conductive layer is bonded to the metallic piece and the selected core by the ultrasonic welding. This prevents the metallic piece from being deformed after the ultrasonic welding has been done. For this reason, the mechanical strength of the bonding portion between the single core and conductive layer can be further improved, and an electric connection therebetween can be made more surely.
The above and other objects and features of the invention will be more apparent from the following description taken in conjunction with the accompanying drawings.